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Discussion Starter · #1 ·
I had a 8 inch sort of hairline crack in my bathroom drywall (photo attached) that i patched using mesh tape and spackling (DAP drydex). I applied 3 coats sanded everything waited a few hours and painted. Looked good. After 1 week the mesh tape is starting to show up (photo attached). Any idea of what i did wrong?
Thank you
 

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#1, Should have used paper not mesh tape.
"Spacke" is for filling tiny nail holes not for taping. Should have used All purpose drywall compound.
The rest just looks like a really bad sanding job.
If you can feel flaws there going to show, no amount of primer or paint is going to "fix" it.
The key is thin coats so there's almost no sanding needed and even then just on last coat.
 

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Discussion Starter · #3 ·
joecaption said:
#1, Should have used paper not mesh tape. "Spacke" is for filling tiny nail holes not for taping. Should have used All purpose drywall compound. The rest just looks like a really bad sanding job. If you can feel flaws there going to show, no amount of primer or paint is going to "fix" it. The key is thin coats so there's almost no sanding needed and even then just on last coat.
Yup. First time doing this... Given mesh was thick i had to apply more spackle but definitely inexperienced shows. However it did not look bad before the tape started to pop out. All photos show the patching after the tape popped out. So maybe this is because i used spackle?
 

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That will work better.Thin it a little and mix good.Use with paper tape.If I was doing it I would take a utility knife and cut a angled groove along that crack to get more mud in the joint and form a better bond to the old material.
 

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Discussion Starter · #11 ·
How many coats for a smooth finish? I was told 2-3 coats using a large tapping knife on each coat. Is that right? Also dry time in this says 24h does that mean a 3 day job? Or i can apply additional coats before 24h
 

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I would cut the crack with a utility knife on and angle to give a better bond.Use some durabond 90 to prefill and then bed some fibafuse or paper tape.Put a light even coat of durabond over it to wet the outside of the tape and let set for a couple hours.I would apply this with a 6" knife.I would then scrape it with a knife to knock down any high spots.Should not be any if you laid a good first coat.Lay another smooth coat of Durabond 90 over the first coat with a 10" knife.Wait a few hours and then scrape it down with your knife and put a final coat on of premixed topping thinned slightly with a 12" knife.Let cure 24 hr. Sand and prime .
Can be done in a day except for the sand and prime if it's in your house and your there.
That is why they call it hot mud.
If you can't find Durabond in your area HD has USG Easysand.Get the 90 minute if it's the first time your using it.Clean your tools up after use as this sets up by a chemical reaction other than evaporation and will harden up even submerged in water.
 

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Discussion Starter · #13 ·
mako1 said:
I would cut the crack with a utility knife on and angle to give a better bond.Use some durabond 90 to prefill and then bed some fibafuse or paper tape.Put a light even coat of durabond over it to wet the outside of the tape and let set for a couple hours.I would apply this with a 6" knife.I would then scrape it with a knife to knock down any high spots.Should not be any if you laid a good first coat.Lay another smooth coat of Durabond 90 over the first coat with a 10" knife.Wait a few hours and then scrape it down with your knife and put a final coat on of premixed topping thinned slightly with a 12" knife.Let cure 24 hr. Sand and prime . Can be done in a day except for the sand and prime if it's in your house and your there. That is why they call it hot mud. If you can't find Durabond in your area HD has USG Easysand.Get the 90 minute if it's the first time your using it.Clean your tools up after use as this sets up by a chemical reaction other than evaporation and will harden up even submerged in water.
thanks for all the details. The paint i have is paint and primer together. Should i prime regardless?
 

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In using a "big" knife the way a drywall guy would do it is like to put the first coat on with a 5" knife remove it with a 6" second coat put on with a 6 remove with an 8 third coat on with an 8 off with a 12" Since a DIY doesn't usually have all these different sizes don't get a big knife and try to use the whole knife to do all the coats. You will end up with a big lump. the first couple coats just use part of the knife.

This is what we mean by feathering. This can be done with a 6" and
12" using the 6 to apply and the 12 to remove.
 
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